Apparatus and method for treating thermoplastic yarns

ABSTRACT

An apparatus for treating a thermoplastic, synthetic yarn at a high rate of production, whereby the treated yarn has a high degree of crimp resulting in an enhanced, uniform bulk throughout the length thereof. The apparatus comprises means for heating the yarn to a substantially plastic state, a friction-type falsetwist unit positioned to receive the yarn in advance of the friction-type false-twist unit, a pin-type false-twist unit positioned to receive the yarn from the friction-type false-twist unit while at least a portion of the yarn remains plastic for imparting additional false-twist in the same direction as the false-twist inserted by the friction-type false-twist unit. This additional false-twist is applied between the friction-type false-twist unit and the pin-type false-twist unit and the net twist inserted by the friction-type false-twist unit and the pintype false-twist unit substantially equals the total twist desired to be applied to said yarn.

United States Patent Schippers Sept. 17, 1974 APPARATUS AND METHOD FOR 3,670,488 6/1972 Richter 57 774 TREATING THERMOPLASTIC YARNS 3,726,073 4/1973 Stutz 57/157 TS X [75] Inventor: gglrrgaichlppers, Remscheid, Primary Examiner john w. Huckert y Assistant ExaminerCharles Gorenstein [73] Assignee: Barmag-Barmer Maschinenfabrik Attorney, Agent, or FirmParrott, Bell, Seltzer, Park Aktiengesellschaft, Wuppertal, & Gibson Germany [22] Filed: Dec. 15, 1972 ABSTRACT [21] APPL NOJ 315,545 An apparatus for treating a thermoplastic. synthetic yarn at a high rate of production, whereby the treated yarn has a high degree of crimp resulting in an enl Forelgn Appllcatlon y Data hanced, uniform bulk throughout the length thereof. Dec. 23, 1971 Germany 2l64061 The apparatus comprises means for heating the yarn to a substantially plastic state, a friction-type false- [52] US. Cl 57/34 HS, 57/77.3, 57/77.4, twist unit positioned to receive the yarn in advance of 57/77.42, 57/157 TS the friction-type false-twist unit, a pin-type false-twist [51] Int. Cl D02g 1/02, D02g 1/04 unit positioned to receive the yarn from the friction- [58] Field of Search 57/77.3, 77.4, 77.42, 77.45, type false-twist unit while at least a portion of the yarn 57/157 TS, 34 HS remains plastic for imparting additional false-twist in the same direction as the false-twist inserted by the [56] References Cited friction-type false-twist unit. This additional false-twist UN T T S PATENTS is applied between the friction-type false-twist unit 2 939 269 6/1960 Dobson 5.1/77 4 and the pin-type false-twist unit and the net twist in- 3,516,240 6/l970 Fain 5 7/157 TS Smed by the friction-type false'twist unit and the 3,643,412 2/1972 Maeda et aL 57/77 4 X type false-twist unit substantially equals the total twist 3,656,288 4/1972 Gilchrist 57 774 x desired t be appli d t said yarn.

3,659,408 5/1972 Burr 57/77.4 X l 3,668,855 6/1972 Leeson et al, 57 34 HS x 8 C 4 Drawmg figures a l3 l 5 il 2 f l 4 i I 0' a l 4a (00L l 41 i: 3

I N w: i. C ,7 t v .mO

APPARATUS AND METHOD FOR TREATING THERMOPLASTIC YARNS This invention relates to the manufacture of textured synthetic yarns, and in particular, to a method and apparatus for texturizing thermoplastic yarn which, after suitable heating to its plastic state, is subjected to at least two immediately successive, different types of falst-twisting operations.

False-twist texturing processes, in which the yarn, after it has been heated and false-twisted, is reheated and false-twisted in the opposite direction, are already known. See, for example, British Pat. specification No. 788,944 and French Pat. specification No. 1,267,239. Furthermore, it has also been proposed to subject a heated yarn to two immediately successive false-twist operations by means of the same twister. See, for example, unexamined German Pat. application No. 2,014,516. In this latter process, a yarn which has traveled over an annular friction surface rotating around a stationary axis is sharply diverted and travels back over the same friction surface in the opposite direction.

Prior art methods and devices utilizing friction or pin-type false-twist units separately, each present persistent difficulties-For example, the speed of rotation of conventional-pin-type false-twist units, according to present experience, appears to be limited to about 800,000 r.p.m., which results in an uneconomical rate of production. A friction-type false-twist unit on the other hand, can produce false-twisted yarn at several times the rate of pin-type units. At these high rates of speed, however, the tension on the yarn is so great that the formation of a completely effective twist trap is very difficult. This results in slippage of twist past the friction surface, yarn, breakage, and undesirable variations in the amount of twist applied thereto.

It is therefore an object of this invention to provide a method and apparatus which eliminates the problems described above.

More particularly, it is an object of this invention to provide a method and apparatus for producing hightorque, texturized yarn at high rates of speed.

It is another object of this invention to provide a method and apparatus of producing a texturized yarn wherein the high production rate results in a yarn which, after having been false-twisted by a friction-type unit, still has in its interior filaments a sufficient degree of remaining plasticity to be false-twisted again by a pin-type unit positioned in yarn receiving relation to the friction-type unit.

In accordance with the present invention as set forth in the foregoing objects, it is proposed to combine a friction-type false-twisting unit, with a pin-type falsetwisting unit which receives the yarn which would normally be in the u ntwisted condition from the frictiontype unit and twists the yarn again in the same direction as the twist imparted to the yarn in advance of the friction-type unit. In this manner, there can be obtained a substantial increase in the twist and in the total torque which can be applied to the yarn, while also substantially increasing the production rate of the apparatus. This is particularly true when the friction-type unit itself is able to apply the major portion of the desired twist per inch to the yarn, since the pin-type unit, traveling at a relatively low speed, is able to prevent untwisting of the yarn and thereby insert any remaining twist which may be necessary. As a result, the reliability of the apparatus is increased.

Another advantage of the proposed invention is distinguished by the fact that a pin-type unit can be combined with a disk or ring friction-type unit which consists of at least three disks or rings rotating on three parallel axes, with the arrangement being varied by axially displacing at least one disk. The particular advantage of this arrangement is that it enables the yarn tension between the friction-type unit and the pin-type unit to be controlled within wide ranges and preferably, to be reduced. In this way, it is also possible to reduce yarn tension after twisting is completed so as to avoid yarn breakage while at the same time increasing the take-off rate up to the maximum permitted by the strength of the yarn.

According to the arrangement desired, the frictiontype unit and the pin-type unit may be driven either together or separately to false-twist the yarn in the same direction.

Some of the objects of the invention having been set forth, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a false-twist apparatus according to the present invention wherein the frictiontype unit thereof comprises three disks rotating in parallel axes;

FIG. 2 is a schematic plan view of the three rotatable disks of the false-twist apparatus shown in FIG. 1;

FIG. 3 is a schematic plan view similar to FIG. 2, wherein one of the disks is moved to a position whereby the tension exerted on a yarn passing over a moving edge of each of said disks is varied; and

FIG. 4 is a perspective view of another embodiment of a false-twist apparatus according to the present invention, having a sleeve-type friction false-twist unit.

Referring now more specifically to the drawings, a false-twist apparatus according to one embodiment of the invention is shown in FIG. 1 and comprises a frame 1 with a friction-type false-twist unit, broadly indicated by reference numeral 2 mounted thereon, with a conventional rotating pin-type false-twisting unit 3 also mounted on said frame 1 below friction unit 2 in yarn receiving relation thereto. As is best shown in FIG. 1, the friction unit 2 according to this embodiment of the invention comprises a disk-column apparatus, comprising three friction disks 4, 5 and 6, also shown schematically in FIGS. 2 and 3, with disks 4 and 6 being concentrically carried by rotatably mounted columns 4a and 6a, respectively.

As is illustrated in FIG. 1, friction-type unit 2 and pin-type unit 3 are driven jointly from a moving drive belt 12, which imparts rotation to drive column 4a. Drive column 4a rotates pintype unit 3 by direct surfaceto-surface engagement with an outer axial surface thereof. Drive column 40 also rotates disk 4, concentrically connected thereto, and disk 5, through a pulleydriven drive box assembly 13. As will be noted, disk 5 is pivotally carried by an arm of drive box assembly 13. Disk 6 is rotated by direct surface-to-surface engagement of column 6a, to which disk 6 is concentrically connected, with rotating pin-type unit 3.

According to FIG. 1, a yarn 7 is conducted downwardly from a delivery source 8 through yarn guide 9 and over a heated surface 11, which heated surface 11 heats yarn 7 to a plastic state. After passing over heated surface 11, yarn 7 passes through yarn guide and then through the friction unit 2, and by contact with an edge of each of disks 4, 5 and 6, all rotating in the same direction, is false-twisted. It will be noted that according to FIG. 2, disks 4, 5 and 6 form a cusp C therebetween through which yarn 7 passes.

The twist imparted to yarn 7 moves back in the yarn to the heated surface R1, and even beyond to the delivery source 8. After passing through the friction unit 2, yarn 7 attempts to untwist as far as possible into its original untwisted state. It is substantially prevented from doing so by the pin-type unit 3, which iserts additional twist. As illustrated in FIG. I, the twist inserted in the yarn between the pin-type unit 3 and the frictiontype unit 2 is in the same direction as the twist in advance of the friction-type unit 2 but the yarn is twisted to a lesser degree. Thus, the net twist inserted by the friction-type unit 2 and the pin-type unit 3 substantially equals the total twist desired to be applied to the yarn. As a result, friction-type unit 2 need not take up the entire amount of twist between the heated surface 11 and the friction unit 2, but only the difference in twist between the heated surface 11 and the friction-type unit 2 and between friction-type unit 2 and pin-type unit 3.

As is illustrated in FIG. 3, disk 5 can be pivoted in the direction of the arrow further onto the axes of disks 4 and 6 so that the disks further overlap each other. In this way, the disks 4, 5 and 6 exert a delivery effect upon the yarn, provided their direction of rotation is suitably selected, so that the yarn tension between friction-type unit 2 and pin-type unit 3 is reduced.

However, it is also possible to apply a breaking effect to the yarn by changing the axial sequence of the disks, or the direction of rotation. In this way, and by suitably adjusting yarn stretch, temperature, and the like, it is possible to compensate for thetension reduced by pintype unit 3.

Because of this novel arrangement of a friction-type unit and pin type unit in combination, a surprisingly full three dimensionally crimped yarn may be thus produced. Because of the high rate of production possible under this arrangement, the interior of the yarn after friction-twisting is still somewhat plastic, so that the twist moving backwards in the yarn is already fixed as a result of increasing internal cooling. After twising on the pin-type unit 3, the yarn is twisted and will spring fully open.

Another embodiment of the false-twist apparatus according to this invention is shown in FIG. 4. As will be noted, the embodiments in FIGS. 1 and 4 are similar. Therefore, prime notation has been added to the reference numerals in FIG. 4 which identify corresponding elements of the invention.

Substituted for the disk-column friction unit 2 in FIG. 1, is a sleeve-type friction unit, broadly indicated by reference numeral 20, mounted on a frame 1' and having a rotatably mounted sleeve 21 positioned in horizontally offset relation to a pin-type unit 3. Yarn guides 22 and 23 serve to position yarn 7' for being received into rotating sleeve 21 where yarn 7' is falsetwisted by angularly engaging longitudinally opposed moving edges thereof, and to reposition yarn 7 after leaving rotating sleeve 21 for being received into pintype unit 3'.

Friction-type unit and pin-type unit 3 are jointly driven by means of a moving belt 12', which rotates by engagement therewith a column 24 mounted on frame 1' which in turn rotates pin-type unit 3' by direct surface-to-surface engagement with an outer axial surface thereof. Pin-type unit 3' drives a frame-mounted column 25 by direct surface-to-surface engagement. whereby rotational movement is transferred to sleeve 21 through a series of belts and pulleys broadly indicated by reference numeral 30.

As is described above, the apparatus and method according to this invention allows texturized yarn to be produced at a high rate of production while nevertheless enhancing the bulking characteristics of the yarn.

It will be understood that various details of the invention may be changed without departing from the scope of the invention. Furthermore. the foregoing description is for the purposes of illustration only, and not for purposes of limitationthe invention being defined by the claims.

That which is claimed is:

1. An apparatus for treating a thermoplastic. synthetic yarn at a high rate of production, whereby said treated yarn has a high degree of crimp, resulting in an enhanced, uniform bulk throughout the length thereof, said apparatus comprising:

a. means for heating the yarn to a substantially plastic state,

b. a friction-type false-twist unit positioned to receive the yarn from said heating means for false-twisting said yarn in advance of said friction-type false-twist unit,

c. a pin-type false-twist unit positioned to receive said yarn from said friction-type false-twist unit while at least a portion of said yarn remains plastic for im parting additional false-twist in the same direction as the false-twist inserted by said friction-type false-twist unit and between said friction-type falsetwist unit and said pin-type false-twist unit, the net twist inserted by the friction-type false-twist unit and the pin-type false-twist unit substantially equaling the total twist desired to be applied to said yarn, and

d. means for successively guiding said yarn through the heating means, through said friction-type falsetwist unit, and through said pin-type false-twist unit.

2. An apparatus according to claim 1, wherein said friction-type false-twist unit and said pin-type falsetwist unit are positioned closely adjacent each other for providing a short yarn path therebetween, thereby minimizing dissipation of heat from said yarn.

3. An apparatus according to claim 1 including a driven belt and, wherein said friction-type false-twist unit and said pin-type false-twist unit are both driven by said drive belt.

4. An apparatus according to claim 1, wherein said friction-type false-twist unit comprises a plurality of disks, each mounted for rotation in the same direction and forming a cusp for passing a yarn therethrough, whereby said yarn is false-twisted by successive engagement with an edge of each of said disks.

5. An apparatus according to claim 1, wherein said friction-type false-twist unit comprises a rotatable tubular sleeve for passing a yarn therethrough, whereby said yarn is false-twisted by successive angular engagement with longitudinally opposed edges of said tubular sleeve.

6. A method of treating a thermoplastic, synthetic yarn by imparting a predetermined amount of falsetwist thereto, which comprises the steps of:

a. heating the yarn to a substantially plastic state;

b. falsetwisting said yarn by passing said yarn through a friction-type false-twist unit; and

c. false-twisting said yarn again while a portion of said yarn remains in its plastic state by passing said yarn through a pin-type false-twist unit and imparting twist to said yarn in the same direction as that imparted by said friction-type false-twist unit the net twist inserted by the twisters substantially equaling the predetermined amount of false twist. 

1. An apparatus for treating a thermoplastic, synthetic yarn at a high rate of production, whereby said treated yarn has a high degree of crimp, resulting in an enhanced, uniform bulk throughout the length thereof, said apparatus comprising: a. means for heating the yarn to a substantially plastic state, b. a friction-type false-twist unit positioned to receive the yarn from said heating means for false-twisting said yarn in advance of said friction-type false-twist unit, c. a pin-type false-twist unit positioned to receive said yarn from said friction-type false-twist unit while at least a portion of said yarn remains plastic for imparting additional false-twist in the same direction as the false-twist inserted by said friction-type false-twist unit and between said friction-type false-twist unit and said pin-type false-twist unit, the net twist inserted by the friction-type false-twist unit and the pin-type false-twist unit substantially equaling the total twist desired to be applied to said yarn, and d. means for successively guiding said yarn through the heating means, through said friction-type false-twist unit, and through said pin-type false-twist unit.
 2. An apparatus according to claim 1, wherein said friction-type false-twist unit and said pin-type false-twist unit are positioned closely adjacent each other for providing a short yarn path therebetween, thereby minimizing dissipation of heat from said yarn.
 3. An apparatus according to claim 1 including a driven belt and, wherein said friction-type false-twist unit and said pin-type false-twist unit are both driven by said drive belt.
 4. An apparatus according to claim 1, wherein said friction-type false-twist unit comprises a plurality of disks, each mounted for rotation in the same direction and forming a cusp for passing a yarn therethrough, whereby said yarn is false-twisted by successive engagement with an edge of each of said disks.
 5. An apparatus according to claim 1, wherein said friction-type false-twist unit comprises a rotatable tubular sleeve for passing a yarn therethrough, whereby said yarn is false-twisted by successive angular engagement with longitudinally opposed edges of said tubular sleeve.
 6. A method of treating a thermoplastic, synthetic yarn by imparting a predetermined amount of false-twist thereto, which comprises the steps of: a. heating the yarn to a substantially plastic state; b. false-twisting said yarn by passing said yarn through a friction-type false-twist unit; and c. false-twisting said yarn again while a portion of said yarn remains in its plastic state by passing said yarn through a pin-type false-twist unit and imparting twist to said yarn in the same direction as that imparted by said friction-type false-twist unit the net twist inserted by the twisters substantialLy equaling the predetermined amount of false twist.
 7. A method according to claim 6, wherein the step of false-twisting said yarn by passing said yarn through a friction-type false-twist unit includes the step of passing said yarn successively over an edge of each of a plurality of suitably arranged rotating disks.
 8. A method according to claim 6, wherein the step of false-twisting said yarn by passing said yarn through a friction-type false-twist unit includes the step of angularly engaging said yarn with an edge of opposing ends of a sleeve rotating around its longitudinal axis. 